Slot closure actuating mechanism



March 20, 1945. I c, PATCH 2,371,976

SLOT CLOSURE ACTUATING MECHANISM Filed Dec. 31, 1942 I8 ARTHUR C. PATcH FIG. 3. 4 46 MENTOR BY al/m,

HIS ATTORNEY.

Patented Mar. 20, 1945 2,371,976 SLOT CLOSURE ACTUATING MECHANISM Arthur 0. Patch, Santa Monica, Calif., assignor to North American Aviation, Inc., Inglewood, C'alif., a corporation of Delaware Application December 31, 1942, Serial No. 470,775

3 Claims.

This invention relates to improvements in actuating mechanism for closures, and more particularly to mechanism for the operation of doors controlling the opening and closing of slots in airfoil surfaces.

In variable lift airfoil surfaces it is customary to provide intersurface slots and to regulate the action of the slot, in allowing a flow of air from one surface to the other, by providing a movable door or doors at the ends of the slot. Variable slots are also frequently used which may be regulated by having one slot wall formed by a surface of a member relatively movable with respect to the fixed member contributing the opposite wall of the slot. Depending upon the configuration of the slot walls and the allowable movement of the one member, the slot may be entirely closed off upon the movement of the members into contact or the slot may be closed somewhere along its length so as to cut off flow therethrough but at the same time, at the mouth or at the mouth and exit of the slot may be left gaps in the airfoil surfaces. Such gaps detract from the aerodynamic efiiciency of the airfoil by creating interruption of the laminar flow and consequent drag. In such a case it is the practice to provide a movable closure whereby the slotted airfoil can be restored to the equivalent of ansubstantlally unbroken airfoil contour at such" times when the slot is not employed.

A variable slot of the type which requires a closure at its mouth is produced in airfoils fitted with high lift flaps. As is well known, such flaps normally carry out the original airfoil contour but can be lowered or pivoted with respect to the fixed main or forward part of the airfoil to provide increased lift at slow speeds. When such flaps are moved into operative position, it is usual for the relative movement of the slot nose with respect to the fixed airfoil section,- to form a slot therebetween extending upwardly and rearwardly from the lower surface to the upper surface.

Such flaps pivot downwardly and for reasons of clearance and due to provision for desirable slot characteristics, the mouth of the'slot is relatively wide and even with the flap innormal position the trough that remains is of considerable width, depth and span.

The present door and its operating mechanism are intended for use in closing off a surface opening of this type when the flap is in normal position; The addition of an accessory of tihs nature should notadd to thecomplexity of the operation of the aircraft and accordingly it is desirable that the mechanism operate automatically in conjunction with the operation of the flap, that it be entirely enclosed within the airfoil surface and that its operation be correctly timed with respect to that of the flap. In attaining this last operational characteristic it is preferable that the door open fully upon initial movement of the flap away from its neutral position and remain open until the flap is again restored to the aligned position.

The objects of the present invention are to provide a closure operating mechanism incorporating the desirable characteristics outlined above and by reference to the accompanying drawing and following description, a full understanding of the construction and operation of this mechanism may be attained.

In the drawing:

Fig. 1 is a sectional view of a portion of a variable lift airfoil fitted with a flap of the slot opening type and with a movable closure for the slot mouth opening;

Fig. 2 is a section similar to Fig. 1 taken at a pointy adjacent the location of theclosure operating mechanism and showing the closure in gap .is a bracket 22 and two or more such bracketsare provided at spaced locations to provide for the complete mounting of the flap 20. This is accomplished at each bracket by means of a pivot 34 at the projecting end of the bracket from which extends a simple link 36 which at its other and may be pivotally connected to the flap as at 38.

Extending spanwise through the airfoil section is a torque tube 24 supported for rotational movement in the brackets 22. Adjacent to each point of support for the flap 20, or adjacent to as many such points as may appear necessary, the torque tube carries collars 26 from which project lever arms 28 and 29. Pivotally connected to the projecting end 30 of each of the arms 28 are pushpull links 32 which each in turn rigidly connect to the flap 20 adjacent its leading edge. Thus it is obvious that with this mounting of the flap and the linkage connection to the torque tube, rotation of the latter will cause the flap to be swung rearwardly and downwardly to a displaced position as shown in Fig.3 and this movement will create an intersurface slot between the nose of the flap 20 and a curved plate 68 which forms a rear wall for the airfoil portion Ill-I2.

The mechanism employed to cause rotation of the torque tube 24 is conventional and may consist of a hydraulic motor such as is fragmentarily shown at 44. The end 42 of the piston of this motor is pivotally connected by a link 40 to one of the arms 29 and thus by remote control of the motor, the pilot or operator can cause the raising and lowering of the flap 2,0.

As previously stated, the streamline profile of the airfoil portion defined by the upper and lower surfaces I and I2 is continued to a narrow trailing edge by the surfaces of the flap 20 but due to provision for the opening of the previously mentioned intersurface slot between the nose of the flap and the rear end of the fixed airfoil portion, this contour would be interrupted by a gap on the lower side of the combination to the rear of the spar l4 and the gap would be roughly of triangular section extending halfway into the depth of the airfoil. In order to cover this gap, a closure or door I6 is pivotally mounted as at '8 in the gap in flush continuation of the surface 12.

With the flap lowered, as in Fig. 3, and the slot opened, it is necessary that the door be swung back to allow unimpeded airflow through the slot. This swinging back of the door. is accomplished automatically in consequence of the initial movement of the flap. Likewise return of the into a guide portion 52 characterized by bifurcated arms 54 which straddle the torque tube 24 as shown with just suflicient clearance'to perj mit sliding movement of the arms on the ,tube.

I The member 52 may also be bifurcated in a direction parallel tothe plane of the drawing so that, in such a case, there would be in actuality, fourof the arm Theslot formed by this second bifurcation would extend. nearly the full length of member 52 to terminate at the curved dotted line shown thereon.

. Amxed to the torque tube 24 is a collar 56 and this is positioned between the two pairs of arms 54. This collar projects along a portion of its periphery in the form of a flange and the flange portion has cut therein a cam slot of which the major ortion 60 is substantially concentric to the tube 24. 'The remainder 64 of the slot extends at an angle to the portion 60 being directed inwardly toward the tube. There is a pin 62 extending between the two faces of the member 52 and with the door closed as in Fig. 2, this pin exfully open the door to the position shown in Fig, 3 wherein the free edge of the door l6 seats in a groove portion 10 formed in the edge of the curved plate 68. As therotation of the tube 24 continues, the pin 62 enters the slot portion fill and the radial movement of the pin ceases but nevertheless, the pin does not interfere with continued lowering movement of the flap 20. When the tube 24 is later turned in a clockwise direction to retract the fiap, the cam slot moves past the pin 62 until the portion 64 again comes into engagement therewith and is effective to cause movement of the pin radially toward the center of the tube with consequent closing movement of the door l6, followed by complete return of the flap to neutral.

While this application of the present mechanism has for purposes of illustration been made in connection with a slot closure in an airfoil, it is capable of being employed in many other installations where its functioning would be of advantage and hence it is not intended that the invention be limited in any way by its association with such an installation but only in conformity with the scope of theappended claims.

I claim as my invention:

1. An aircraft wing system comprising a fixed wing and a movable member associated therewith in a slot-forming relationship, a rotatable actuating element for the operation of said movable member, a closure element normally forming a streamlined continuation of the aligned surfaces of said wing and said movable member, said closure element having a pivotal support upon said wing and a spaced pivotal connection, a variable radius cam means fixedly attached to rotate with said actuating element, a link engaging said cam means and the said spaced pivotal connection of said closure element whereby rotation of said actuating means for slot-forming operation of said movable member rotates said slot closure element into its slot-opening position, parallel links pivotally supporting the movable member at spaced points from a pivot axis supported by the fixed wing, and a force transmitting linkage having elements interconnected at a pivot point, the said linkage operably interconnectin the movable member with the rotatable actuating element, the said parts being so organized that the said pivot axis, the said pivotal connection, and the centerline of the rotatable actuating element form the apexes of a triangle on one leg of which lies the said pivot point when the movable member is in tends through the cam slot being disposed at the a neutral position, and whereby the said pivot point is displaced to lie on an adjacent leg of the triangle when said movable member is moved to fully operative position.

2. In an aircraft wing system, a main fixed and pivotally connectedto said lever, whereby from the tube. Because of the bearing of the arms 54 on the surface of the tube, this movement is forced to occur radially outward from the tube. The movement of the pin and consequently upon rotation of the actuating member the said flap is caused to move rearwardly and downwardly with each, point of pivotal support on the flap constrained to follow an arcuate path centered'on the pivot point of attachment of the respective link to its bracket so that a slot is opened between the nosev of said flap and the trailing tached to rotate with said actuating member, said flanged element having a cam slot of varying radius from its center otrotation cut into said flanged portion, and interconnecting means pivotally connected adjacent one terminal portion to said closure element and having a pin associated with, its opposed terminal portion engaging the said cam slot in said flanged element. a pair or fork arms extending in substantial parallelism from said opposed terminal portion to embrace and be guided upon said actuating member whereby said interconnecting means is constrained to linear motion and causes slot closure operation coincident with initial flap movement rearwardly.

3. The combination in a control surface installation, a control surface pivotally mounted at the ends ofparallel swinging links; the said links in turn being pivotally connected to fixed structure; an actuating member mounted to respond to control impulses; a lever extending from said actuating member to pivotal-connection with a rigid projection extending from the control suredge oi said fixed-wing, a flanged element at- 4 tuating. member; an interconnecting member formed with fork arms slidingly embracing the actuating, member; the interconnecting member extending substantially radially with respect thereto and terminating in a pivot connection;

a hinged door pivotally mounted adjacent the nose or the control surface; a pivot connection,

i attached to the said door oflset from the hinge axis thereof and operably connected to the pivot connection on the said interconnecting means;

and a cam follower projecting from the said interconnecting means, at a point on the line drawn through the said pivot connection and the axial centerline of the actuating member, to engage said slotted cam; the said parts of the combination being so organized as to cause full opening of said door coincident with initial rearward and downward movement of the control surface about a center of pivotation moving on the arc of a a face; a slotted cam plate extending from said ac-- 

